

const _keyStr: string = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='

const encode = (input: any): string => {
    let output = ''
    var chr1, chr2, chr3, enc1, enc2, enc3, enc4
    var i = 0
    input = _utf8_encode(input)
    while (i < input.length) {
        chr1 = input.charCodeAt(i++)
        chr2 = input.charCodeAt(i++)
        chr3 = input.charCodeAt(i++)
        enc1 = chr1 >> 2
        enc2 = ((chr1 & 3) << 4) | (chr2 >> 4)
        enc3 = ((chr2 & 15) << 2) | (chr3 >> 6)
        enc4 = chr3 & 63
        if (isNaN(chr2)) {
            enc3 = enc4 = 64
        } else if (isNaN(chr3)) {
            enc4 = 64
        }
        output = output +
            _keyStr.charAt(enc1) + _keyStr.charAt(enc2) +
            _keyStr.charAt(enc3) + _keyStr.charAt(enc4)
    }
    return output
}
// public method for decoding
const decode = (input: any): string => {
    var output = ''
    var chr1, chr2, chr3
    var enc1, enc2, enc3, enc4
    var i = 0
    input = input.replace(/[^A-Za-z0-9\+\/\=]/g, '')
    while (i < input.length) {
        enc1 = _keyStr.indexOf(input.charAt(i++))
        enc2 = _keyStr.indexOf(input.charAt(i++))
        enc3 = _keyStr.indexOf(input.charAt(i++))
        enc4 = _keyStr.indexOf(input.charAt(i++))
        chr1 = (enc1 << 2) | (enc2 >> 4)
        chr2 = ((enc2 & 15) << 4) | (enc3 >> 2)
        chr3 = ((enc3 & 3) << 6) | enc4
        output = output + String.fromCharCode(chr1)
        if (enc3 != 64) {
            output = output + String.fromCharCode(chr2)
        }
        if (enc4 != 64) {
            output = output + String.fromCharCode(chr3)
        }
    }
    output = _utf8_decode(output)
    return output
}
// private method for UTF-8 encoding
const _utf8_encode = (string: any): string => {
    string = string.replace(/\r\n/g, '\n')
    var utftext = ''
    for (var n = 0; n < string.length; n++) {
        var c = string.charCodeAt(n)
        if (c < 128) {
            utftext += String.fromCharCode(c)
        } else if ((c > 127) && (c < 2048)) {
            utftext += String.fromCharCode((c >> 6) | 192)
            utftext += String.fromCharCode((c & 63) | 128)
        } else {
            utftext += String.fromCharCode((c >> 12) | 224)
            utftext += String.fromCharCode(((c >> 6) & 63) | 128)
            utftext += String.fromCharCode((c & 63) | 128)
        }
    }
    return utftext
}
// private method for UTF-8 decoding
const _utf8_decode = (utftext: string): string => {
    let string = ''
    let i = 0
    let c = 0;
    let c2 = 0;
    let c3 = 0;
    while (i < utftext.length) {
        c = utftext.charCodeAt(i)
        if (c < 128) {
            string += String.fromCharCode(c)
            i++
        } else if ((c > 191) && (c < 224)) {
            c2 = utftext.charCodeAt(i + 1)
            string += String.fromCharCode(((c & 31) << 6) | (c2 & 63))
            i += 2
        } else {
            c2 = utftext.charCodeAt(i + 1)
            c3 = utftext.charCodeAt(i + 2)
            string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63))
            i += 3
        }
    }
    return string
}

export default {
    encode, decode
}